Process and apparatus for obtaining



July 15, 19 2 A. w. WAY ETAL PROCESS AND APPARATUS FOR OBTAINING A THICKENED CONCENTRATE 4 Sheets-Sheet 1 Filed Oct. 24, 1945 AN A NM Rm A. A E

I INVENTORS. A M112 0]: uay 4: J0)? Willa/alfalfa M M ATTORNEYS.

J y 1952 A. w. WAY ETAL 2,603,354

PROCESS AND APPARATUS FOR OBTAINING A=THICKENED CONCENTRATE I Filed Oct. 24, 1945 4 Sheets-She et 2 W I TNESSES INVENTORS'" .A. W

v BY Joim W lffl lfil i l 'i ATTORNEYS.

ll/JZIlI/IZ m m I 4 Sheets-Sheet 3 A. W. WAY ET AL PROCESS AND APPARATUS FOR OBTAINING A THICKENED CONCENTRATE July 15, 1952 Filed Oct. 24. 1945 INVENTORS-' Wa yd. 2227/7, W M

A A' iy'ezzWa Ja/m Milan/1M0 BY ATTORNEYS.

ywl TNESSEil 9&

y 15, 1952 A. w. WAY ET AL 2,603,354

PROCESS AND APPARATUS FOR OBTAINING A THICKENED CONCENTRATE Filed Oct. 24, 1945 4 Sheets-S he et 4 Han Ffi IL Nani INVENTORS A Mime/Z Wayq A TTORNEYS.

Patented July 15, 1952 PROCESS AND APPARATUS FOR OBTAINING A THICKENED CON GEN TRATE Alben Warren Way, Philadelphia, Pa., and John William Morton, Brooklyn, N. Y. said Morton assignor to said Way Application October 24, 1945, Serial No. 624,144

11 Claims.

,The usual processesfor the removal of solid matter from flowing streams of water are filtration processes whereby, either with or without sedimentation, water is passed through a filtering medium in order to purify it. In these cases the object is to obtain a pure filtrate, that is to say, pure water, the solid matter removed being treated as waste.

Our present invention is a process by which not only is pure water obtained, but also a dense and valuable concentrate, usually semi-solid, but sometimes containing enough water to .be capable of being pumped, and which is transported from the place where it is produced and stored or processed so that its useful component is separated from useless material and thus reclaimed.

The particular use to which we have applied our process is in the reclamation of particles of coal which are constantly carried down from coal mining regions by streams there arising. This waste at present merely clogs up the streams. But it contains a large proportion of finely divided coal which when separated from the silt or mud with which it is associated is a valuable fuel. This coal we reclaim.

Before the useful fine particles carried by a flowing stream can be separated from the useless particles, there must first be effected a condensation or thickening of the total particles and for ordinary purposes the proper degree of thickening is definitely ascertainable. Our process, therefore, difiers fromordinary filtration processes in that it is not so muchconcerned with the filtrate as it is with the production of a sufiiciently condensed concentrate; that is to say, with a thickened mixture of the removed solid particles with only a small amount of water. .The screening operation by which we accomplish this and which we will now describe is capable of producing the proper degree of thickening or concentration, dependent upon the predetermined amount of solids carried by the stream in a given period as compared with the amount of water permitted to be associated with this amount, so as to best facilitate the removal of the .concentrate and separation of the useful part init from the useless part. The latter processes are known and we do not here describe them. The process herein described and claimed relates only to the process by which we thicken and remove from solids-laden water the solid matter accompanied by enough water to produce this concentrate in condition for subsequent processing to separate the useful from the useless part of the solids.

We will proceed to describe a. mechanism or apparatus for carrying out this process without in any wise restricting our process to this particular apparatus.

Fig. 1 is a vertical cross-sectional view of a thickening chamber and accompanying parts suitable for the practice of our process.

Fig. 2 is an elevation of a series of such thickening chambers, partly in section as indicated by the arrows II-II in Fig. 1.

Fig. 3 is a vertical sectional view of a thickening chamber and accompanying parts similar in principle to that shown in Fig. 1, but showing certain variations for use when a more fluid concentrate is desired.

Fig. 4 is a cross-sectional view of the last named thickening chambers.

Figs. 5, 6, '7, 8 and 9 are vertical cross-sectional views of our thickening chambers, eachfigure showing certain useful variant features which may be applied thereto.

Figs.-10 and 11 are respectively cross-sectional and 'elevational views showing the use of a doub nozzle to clean the screen.

Figs. 12 and 13 are cross-sectional views or the screen showing the double nozzle and also mechanism for cleansing the inner side of the screen or screens.

Fig. 14 is an elevational view of the cleansing mechanism of Fig. 13.

Figs. 15 and 16 are cross-sectional views showing the addition of scrapers on the inside of the screen or screens.

Fig. 17 is a detailed sectional view showing a rubber covering for the jet nozzle whereby the jet is made more powerful by concentration.

In the accompanying drawings, I isv a stream of water carrying finely divided solid matter. It meets a thickening chamber 2 which receives it and allows it to flow from near its top toward the bottom of the chamber where it is discharged through a screen. This thickening chamber has an opening 3 for the entrance of the stream of water in the region of its upper end. This entrance is controlled by a gate .4, moved up and down by a rod 5, the reciprocation of which is accomplished by opposed pressure cylinders 6, 6 preferably controlled remotely from an operating station, whereby the gate of the entrance to the thickening chamber is maintained open or closed for-the desired intervals. To prevent the entrance into the chamber of unduly large solids, ,a coarse screen 9 guards the inflow of the stream on the outside of the gate.

II) is the outlet of the thickening chamber, at

3 or near its bottom. It forms a frame for a screen I I which, as shown, is vertical, although inclination is permissible. This screen is very fine and is sectionalized by both horizontal and vertical supporting members so that notwithstanding its fineness it is capable of resisting the water and other pressure to which it is subjected. There is another coarse mesh protecting screen l2 on the inside of the settling chamber which prevents too large solids from being carried against the fine screen H. The bottom of the chamber is contracted to form a sump l5 having. an exit 16 alon its bottom controlled by a valve H, the opening and closing of which is accomplished by opposing pressure cylinders l8 of which the piston is attached to an endless chain l9, trained around idle sprockets and also. around the sprocket 20 on the valve pivot. The, pressure cylinders are preferably subject to remote control.

A baflie plate is mounted more orless centrally in the thickening chamber. It-extends downwardly far enough to prevent direct impact of the incoming streamagainst the fine screen I land to cause the flow to take a generally horizontal direction as it approaches the screened outlet.

On the outside of the screened outlet is a nozzle having a long narrow outlet slot'extending across the Width of the fine screen and capable of projecting a jet of water under considerable pressure against the screen from the outside, the purpose of which jet is to keep the inner surface and meshes of the screen clean by forcing from it any accumulation of solid matter clogging it. The nozzle 30 is fixed on a framelike structure-3l guided for up and down movement by guides 32 on the rear wall of the chamber and reciprocated by acrank disc 34-with which the frame is con- -nected by a rod 33. The shaft of the crank disc 34 has a worm wheel 35 driven by-a worm 36 on a shaft 31 running along the platform, with identical'arrangement for moving the crank discs of other similar thickening chambers. The shaft -31 is operated by a motor- 38 and reduction gear- .m 39 .J I

-- The nozzle 30 is suppliedby a water line 40 from which proceed branches, each with a flexible or extensible component 4| and a spreading end 42. The nozzles may be shut off by remotecontrol-(not shown) or by hand valves 43.

Below the valve which controls the bottom outlet I6 is an elongated conduit withinavhich operates a-screwconveyor which by continual rotation carries with it to a desired point of discharge all the concentrate produceddn and removed from the thickening chamber.

We have described a single thickenin chamber, but they are usually arranged in series. In Fig. z-may be seen a'series of six such chambers placed in juxtaposition to each other,-having. their inlets and outlets at a common level, and arranged so that the control of their inlet gates,

the control of their bottom valve outlets, and control of the jets for their screened-outlets is accomplished in proper sequenceby suitable mechanism.- The jet of water from the nozzle'30 whereby the outlet screen is maintained in proper condition forits work is reciprocated vertically according to a timed schedule which is the same for all of the sixchambers in the seriesto which we have made reference.

- -The operation of our process is as follows:

Solids-laden water is constantly a'dmitted through the intake to, for example,- flve of these thickening chambers, the sixth being excepted because its gate is at this time closed. Under these circumstances each one of these thickening chambers contains water carrying finely divided solid matter flowing down into it and going to the bottom until the water level is above that of the screen H and thereafter flowin out of it through the outlet screen for, say, 25 minutes; but thereafter by closure of the entrance gate no further water is admitted for a time, say, five minutes. The sizeof the intake and the outlet and the fineness of the screen are so related as to create a head of water in the thickening chambercausing a constant flow through the screen under the pressure of this head. The pressure of the water'jet from the nozzle 30 is much greater than the pressure under which water escapes through the screen H, and this enables the jet as it moves constantly up and down over the screen to clear its apertures of any clogging material. The screen ll thus checks the solids within the chamber, preventing them from passing out but allows free passage of clear water. Consequently the solids-content of the chamber continually increases (this is the thickening process) until the ratio of solids to water in the chamber has substantially reached a predetermined figure. This time interval is determined by the percentage of solids in the streams and the rate of flow through the screen, and having been determined the operation i correspondingly controlled. At the end of the interval the flow of back-wash from the water jet is stopped, the intake gate is closed, and the level of the water within the thickening chamber fallsas it'runs through the screen until the level is below the lower edge of the screen. What is left in the sump l5 consists of solids with some liquid thickened or condensed to the desired ratio of solids to water. This residue in usableform is now drawn off by opening the valve at the bottom, permltting all of the concentrate to flow downthrough the valve. into the .circular chamber below, from which it is carried away by the screw conveyor to the place of reclamation of the desirable portion of the solids. The percentage of solids to liquid in this thickened residue is inthe ratio of the total solids accumulated by the thickening process to the amount of water in the sump, which in turn depends upon the cubic capacity of the sump measured from the bottomof the screen down to its lowest point.

When the thickened residue has been; drawn off the valve is closed, and the entrance :gate opened for the required length of time, the flow of the water jet from the nozzle 3}) alsorecommenceswith production of a similar concentrate, and thus the process remats itself. By properly proportioning the periods during which each gate is closed or open and arranging for the proper sequence of this a between the several thickening chambers in the series, a continuous operation of .our process is secured with nointerruption by reason of thetemporary intermission of the outflow in anysingle settling chamber.

To best secure this :continuous sequence of operations remote control of the operations, preferably by alr'pressure, at a suitablylocated operating station is desirable. In the installation'shown this is directly over the series of chambers. Manual operation of this control is possible but not convenient.

The total amount of solid particles carried'by the gates and valves is calculated and adjusted that the proportion of solids to liquid contained in theinflowing stream is sufficiently constant to permit a constant timing of the gates and valves in order to yield a concentrate of the volume and consistency desired; but if the proportions of solid to liquid varies 'inthe stream from time to time, ascertainment of this variation is made and the timing altered to correspond, and this variation may if desired be accomplished automatically so that there always is produced a concentrate which has been thickened to the desired extent.

-We have thus far described a typical apparatus useful for the practice of our process, and have described the general nature and operation of the thickening process which may be: carried on in such an apparatus; but as the proportion of solids to water in one or another infiowing stream varies, and also the size, nature and specific gravity of the particles, variant methods of operation and differing apparatus become necessary to meet these varying conditions. We will now describe certain modified forms of apparatus to be used according as they may berequired to take care of such variations. Under certain circumstances, as for example, where the solids-laden stream contains only very fine particles, it sometimes becomes desirable that the thickening process be not carried far enough to produce a semi-solid capableof mechanical transportation but be kept more liquid and'of a consistency capable of being pumped. For this purpose, in Figs. 3 and 4 an apparatus is shown in which the sump is larger and the discharge through the valve l'! is into a tank '46 from which the concentrate is removed by a pump 41 discharging through an outflow pipe '48. In this apparatus clear water which passes as a jet through the nozzle 30 and plays against the outside of the screen, is obtained from the outgoing clear water which has passed through the screen. This is accomplished by the formation of a large trough 50 below the outgo side of the screen from which sufficient clear water for this purpose is drawn by pipe line 5| to pump 52 which forces it through pipe line 53, to header 54 from which, it is distributed by pipes 55 to the nozzles which are used in connectionwith each ofthickening chambers shown in Fig. 4. The effectiveness of the jet may be thus increased. In this apparatus (shown in Figs. 3 and 4) the operation of the valve H is effected not from. pressure cylinders in the space below the settling chambers, as in the apparatus shown in Figs 1 and 2, but by means of a pressure cylinder 60 located at the operating station. The piston of this cylinder operates a crank on a shaft 6| carrying a sprocket around which is trained a sprocket chain which under guidance of idlers is led down and around the pulley 64 on the shaft of the valve [1. I

Fig. 5 illustrates by a vertical section a variation in the construction of the thickening chamber especially useful where'the inflowing solidsladen stream carries with it a considerable quantity of larger solids which are capable of removal by gravity. Accordingly in this form the bafile plate 25 which stretches across the thickening chamber from side to side is. prolonged downward toward the bottom of the chamber, the lower portion constituting acoarse screen 26 of, say,

about inch mesh. 'There is a deflecting projection 21 at the lower end of the solid portion of the plate which protects the screen below it against the impact of too large or too solid pieces directly hitting the screen; and at or near the bottom of thisscreen and on the intake side is a collecting trough 28 from which particles falling in front of the screen are from time to time removed. It will be noticed that in this form the coarse screen is directly in front of the fine screen and the stream of water flowing through the thickening chamber passes almost horizontally from one screen to another, although the head of water is about the same on both sides of the bafile plate.

In a variant construction shown in Fig. 6 most of the parts are similar to those shown in Fig. 5, but the coarse screen instead of being at the bottom of the. bafiie plate is morenear to its middle and somewhat above the level of the fine: screen. Thus part of the water flowing through the coarse screen passes across to a point opposite to 'or above the top of the latter screen causing a downward flow across the face of said screen as well as through it, giving a showering or cleaning action over the intake face of the screen. This further tends to carry retained solid matter toward the bottom of the thickening chamber. This downward flow, however, is not a free flow because the chamber is completely filled but is a current passing downward to the pocket or reservoir at the bottom of the thickening chamber. This facilitates the deposition of solid matter at the bottom of the thickening chamber. At the bottom of the entrance side of the thickening chamber a trough 10 containing a screw conveyor receives and removes all solid matter which falls therein after being held back by the protecting screen 26.

In the variant construction shown in Fig. 7 the removal of this falling material or, coarse sediment is otherwise effected from a bottom trough II and the bottom of the other part of the thickening chamber is made with a rounded contour I2 and fitted with a series of vanes 13 near the bottom to take advantage of the circular motion of the water created by the downward flow across the face of the fine screen and down to the rounded bottom. These vanes are adjustable and are so adjusted, especially the one which the flow first meets, that the portion of the fiow nearest the face and therefore most heavily laden with solid matter passes below its lowest edge, with production of settlement at the bottom of the chamber. This vane as well as the others. acts to hold the solidsladen water or to retard its return, allowing the water t fl w away as the solid matter goes to the bottom.

In Fig. 8 a construction is shown in which the fine screen II is inclined in a manner to give certain advantages. It permits the use of greater screening surface and allows for a still greater circular flow of the currents on its intake side, for due to the inclination of the screen much of the solid matter automatically falls away toward the bottom of the chamber and is gently pushed under the edge of a cross plate 15, the position of which may be made to correspond to the amount of the current which it is desired shall flow beneath it. The plate thus materially assists in the separation of the solid matter from the water which is circulating just above it. In Fig. 9 the same construction is shown but in place of the plate 15 are substituteda number of cross vanes 16- in anfinclined position which likewise assist the separation of solid matter from the water circulating above it.

.In all the forms of apparatusthus far described the water pressure which causes the screening operation to proceed constantlyand effectively is due to a head of water maintained in or over the thickeningchamber, but substantially'the same processmay be carried on if solids-laden water or other fluid is fed under pressure, as by pumping, to the thickening chamber although for this purpose somewhat variant apparatus is called for.

Figs. 10 and 11 are respectively sectional and elevational views of a modifiedform of means by which back wash isaccomplished. Where the proportion'of very. fine solids carried by the stream of water is high there .is a. greater tendency for .thesolids to clogand .check the action of the line screen. To prevent this it becomes desirable to increase the efiiciency of the back wash by fitting the structure ill with a second nozzle 39 producing a second horizontally extended jet ashort distance above the othernozzle 3B. These are so spaced that with the same constant reciprocation of the frame each half of the screen receives twice asmuch back wash as would otherwise be the case. If necessary more of these nozzles than the two shown may be provided.

Fig. 12 is a vertical sectional view of a variant construction in which in addition to the duplicate jet nozzles on the outside of the screen two stationary nozzles 80, 80 discharge streams of water downwardly over the intake side of the screen. These nozzles 80 are connected with a water pipe BI which supplies the water whereby these nozzles project the jets down and across the screen, thus supplementing the jets on the outgo side of the screen in keeping the screen free from clogging.

- In Fig. 13 is shown in vertical section a variant apparatus in which'the action of the screen II is supplemented by the action of a coarser screen 82 parallel with it but situated on its intake side so that a part of the screening action is efiected by this second screen. Both of these screens are associated with vertically reciprocating nozzles 80, 80 on the intake side by which the cleansing of the screens is assisted by downward jets of water supplied to these nozzles by water pipes 8|, as they move up and down the intake side of the screens.

'The water pipe 8| isheld for vertical reciprocation in a guideway 83 and is connected with a water supply line Ma, the union-fixture Bla having a pivotal connectionwith the reciprocating rod 33a which may begiven vertical movement by a crank on the shaft 31. There are aligned guide rods 84 fixed on the lower nozzles 80, moving in guideways 85 below the bottom of the screen 82. The nozzles 80 move in unison with nozzles 39 on the outside of the screen ll so that any solids liberated from the screen by action of nozzles 30 are immediately caught and carried off by the downward action of nozzles 80.

Fig. 14 is an elevation of the double reciprocating nozzles 80 as seen from the left in Fig. 13.

Fig. 15 shows how a series of screens of different meshes can be advantageously employed in combination with stationary as well as reciprocating jet-nozzles and scrapers. The added screen 86 is of coarser mesh than the screen 82 which in turn is of coarser mesh than the screen II. It is washed by a stationary nozzle 81 on the inside of thescreen and near its upper part. This nozozle 81 is supplied by a water line 88. Another stationary jet-nozzle 89 supplied by the water pipe 90 is located just inside and below the fine screen H in order to clean the bottom of. the screening and also to helpv to transfer the fine silt downwardly into the region of accumulation [5. The nozzle arrangement here shown and its water supplying means and moving means is like that shown in Fig. 13, but the intake side of the screen II is kept free from clogging accumulation of solid matter by the use of horizontal scrapers 8| fixed on a vertically reciprocating rod or rods 82 guided at 83 and 85 and connected with the union-fixture which is pivotally connected to the rod 33a. The scrapers can be solid or semi-flexible or of rubber and move with a sliding fit along the inside of the screen II. The system shown in Fig. 15 has advantages. It provides a compact unit capable of keeping the screens clean and free from damage while working at high capacity. By a series of screening actions the Water containing only the finest particles reaches the finest screen II where the solids are stopped and rapidly forced down to the sump by the action of the scrapers.

Fig. 16 shows an arrangement similar to Fig. 13 but with scrapers working on both screens 82 and II.

From the typical arrangements which have been shown it will be understood that any advantageous combination of screens and any number of screens, with stationary or moving washing jets and scrapers can be used to meet varying conditions.

Fig. 17 shows a fixture of rubber-like material put around the ejection slot of the nozzle 30. Its mouth is flared upward and downward and it reaches the screen with its rounded lips, having a sliding fit in its motion. The beneficial effect of its action lies in setting up a concentration area of jet force within its flare, penetrating the screens and forcing back any solids caught in their channels and so that they are liberated for accumulation inside the screen, while when plain nozzles are used the force of the jet is less concentrated and less effective.

Having thus described Our invention, we claim:

1. The apparatus for deriving a concentrated mixture of solid and liquid material from a solidscarrying stream of water which comprises a thickening chamber, a gated entrance in the region of the top of said chamber for admission of the stream by natural flow, an outlet near its bottom having a screen of such fineness as to retain solid matter in the chamber, the size of the entrance to the chamber and the capacity of the outflow channels of the screen being proportioned so as to maintain a head of water above the outlet screen and a substantially constant 'flow through the screen so long as the entrance gate is open, with accumulation of solid matter behind the screen; an outlet conduit extending below the bottom of said screen in which the screened liquid escapes to a, level below said screen, a sump at the bottom of the thickening chamber below the lower edge of the screened outlet, said sump and outlet conduit being at opposite sides of the screen, and a valved exit at thebottom of the sump through which the concentrate accumulating in the sump may be removed, said valved exit being free of connection .9. with the entrance gate'a'nd constructed to open and close independently thereof. v

2. Apparatus as defined in claim lincluding additionally a movable nozzle projecting a jet of water against the outflow side of the screen to prevent clogging of the screen, and another nozzle projecting another jet of water downwardly over the intake side of. the screen whereby clogging matter driven back by the first mentioned jet is driven down by the second, and means for moving said movable nozzle in a plane adjacent said screen.

3. Apparatus as defined. in claim 1 including additionally a movable nozzle projecting a jet of water against. the outflow side of the screen to prevent clogging of the screen, and a reciprocating scraper operating against the intake side .of the screen and removing from it clogging matter driven'back by the action of the jet from the movable nozzle, and reciprocating means for moving said jet and scraper in planes adjacent said screen. v

4. Apparatus as defined in claim 1 in which the gated entrance and screened outlet are disposed on opposite sides of the thickening chamber and a bafile plate is mounted crosswise of the thickening chamber, with a portion thereof opposite the entrance whereby the entering stream of water is deflected downwardly and compelled to pass into the sump before passing through the screened outlet.

5. Apparatus as defined in claim 1 including additionally an elongated nozzle directed against the outlet side of the screen, means for reciprocating the nozzle, and means for supplying water to said nozzle under pressure greater than that of the stream of water passing through the screen, whereby an elongated jet of water passes through the screen in a direction opposed to that of the stream and removes solid matter accumulating on the intake surface of the screen.

6. Apparatus as defined in claim 1 including additionally a nozzle movable over the outflow side of said screen and delivering a jet of water thereagainst for the removal of clogging matter, and a flexible covering for the nozzle with lips pressing against the screen whereby the jet of water passing through the nozzle is delivered against the screen in an area restricted by the position of the lips of the covering.

7. The apparatus for deriving a concentrated mixture of solid and liquid material from a solids-carrying stream of water which comprises a thickening chamber, a gated entrance in the region of the top of the chamber for admission of the stream by natural flow, an outlet near its bottom having a screen of such fineness as to retain solid matter in the chamber, a sump at the bottom of the thickening chamber below the screened outlet, the top of the sump and the bottom of the screen being at a substantially common level, the size of the entrance to the chamber and the capacity of the outflow channels downstream of the screen being proportioned so as to maintain a head of water above the outlet screen and a substantially constant flow through the screen so long as the entrance gate is open, with accumulation of solid matter upstream of the screen, said outlet extending below the bot tom of said screen in which the screened liquid escapes to a level below the top of said sump, a valved exit at the bottom of the sump through which concentrate accumulating therein may be removed, said valved exit being free of connection with the gated entrance and constructed to 10 open and close independently thereof; andmeans for.opening and closin the gated entranceand the valved exit in a given sequence wherebythe proportion of solids. to liquids in the concentrate as removed may be-regulated. a

8. The apparatus for deriving a' concentrated mixture of solid and liquid material from a solids-carrying stream of water which comprises a thickening chamber, a, gated entranceiri :the region of the top of said chamber, an'outlet near its bottom having a screen of such fineness as to retain solid matter inthe chamber, thesize of the, entrance to the chamber and the capacity of the outflow channels of the screen being 'proportioned so as to maintain a head ori'water above the outlet screen and a substantially: constant flow through'the screen so long'asthe emtrance gate ;is .open, with accumulation of solid matter behind the screen; a sump atthe bottom of the thickening chamber below the-loweredge of the screened outlet; avalved exit at the bot tom of the sump'throughwhich matter accumulating in the reservoir may be removedysaid valved exit being free of connection with the gated entrance and constructed to open and'close independently thereof, a vertically movable jet projecting water against :the screened outlet in opposition to the fluidoutflow and-capable of timed movementv to regularly subject-all parts of the screen to the actioniof the jetandsrecip rocating means for moving said jet lvertically'aid jacentfsaid screen.

9. The process Iof obtainingla thickened concentrate of finely divided suspended solids and water from a natural stream of water which consists in subjecting the flowing stream to a screening process, with detention of finely divided solid matter on the up-stream side of the screen, causing the screened liquid to flow to a point below the bottom of said screen, continuing such screening process for the length of time required to produce a thickened concentrate having a definite predetermined ratio of solids to liquid, excluding the natural stream from said thickened concentrate, thus isolating a thickened concentrate batch, then drawing off the thickened concentrate batch, and repeating the process.

10. The apparatus for deriving a concentrated mixture of solid and liquid material from a solids-carrying stream of water which comprises a thickening chamber, said chamber havin a gated entrance, said chamber having an outlet near its bottom and a screen of such fineness as to permit liquid outflow and retain solid matter in the chamber, the size of the entrance to the chamber and the capacity of the outflow channels of the screen being proportioned so as'to maintain a head of water above the outlet screen and. a substantially constant flow through the screen so long as the entrance gate is open, with accumulation of solid matter behind the screen; a sump at the bottom of the thickening chamber below the lower edge of the screened outlet; a valved exit at the bottom of the sump through which matter accumulating in the reservoir may be removed; and means in the form of a conduit for carrying the liquid outflow to a point below the bottom of said screen and thereby preventing the liquid outflow from backwashing while said concentrate is discharged, said valved exit being free of connection with the gated entrance and constructed to open and close independently thereof.

11. Apparatus for deriving a concentrated mixture of solid and liquid material from a solidsstream of water. which comprises a thickening chamber, asump at the base of said 'thickeninglchamber, said chamber having a gated entrance intermediate the top and bottom'of said chamber, said chamber having an .outletin- :termediate the top and bottom of the chamber -*and. wholly :below the level of said entrance, a acreenfor :said outlet having a bottom edgeat thetopoi said sump,-a portion of .said'screen being'above the sump, and said screen also having atop edge-.belowthe level of :saidentrance,.said :sereenbeing of such finenessas to retain solid matter in thechambenthe size of theentrance to thechamberand-the capacity of theoutflow channels. of "the-screen being proportioned so as tomaintain ahead 01 water above the outlet scnecnand ,a substantially -.constant flow through thescneen so long as the'entrance gateis :open, with accumulation of solid matter behind the screen; an outlet conduit extending below the bottom ofrsaidscreenin which the screenedliquidescapes tea-level below said .screen, a sump at the :bottom of the thickening chamber below the lower-edge of'the screened outlet, said sumpend outlet conduit being at opposite .sides of the screen, and a valved exit at the bottom of the sump through which the concentrate accumulatin .in the :sump may be removed, :said valved .exitibeing free. ofconmection 'with the entrmcevgatennd constructed to:open'and.close' indepeniientiythereof.

ALBENWARREN WAY. .JQHN .MORTON.

REFERENCES CITED The followingreierences are 01' record in the file of this patent: 1

UNITED STATES PATENTS Number Number Name Date Bennett et a1.. Dec. 7, .1897 Wackerow Jan. 5, 1904 Kneuper Nov. 12, 1907 Waite Nov. 26, 1907 Gardiner Aug. 4, B Keyes Mar. '22, 1910 Marsh Jan. 12, 1915 Cronenberger Sept. 7, 1915 Linden June 24, 1919 1': Hunt Nov. 2, 1920 'Wichman .May 16,1922 Giesler Oct. 3, 1922 Price July 28, 1925 Bailey et a1 May 25, 1926 Heaton July 6, 1926 Hapgood Nov. 2, 1926 Fuquaet a1. Mar. 6, 1928 Gard et a1 Apr. 3, 1928 Folta June 24, 1930 Rataiczak July 5, 1932 Paige Aug. 24, 1937 Wuensch Aug. 15, 1939 Monsarrat June 16, 1942 FOREIGN PATENTS.

Country Date Great Britain Dec. 22, .1933 

